I think it boils down to the fact that the sub has nearly 400,000 subscribers, and only a small percentage of them post regularly.

This is the other gagillion people being able to finally participate in a relatively awesome fashion.

I have a habit of checking the 'new' list. Usually it's pretty easy to keep up with what's going on. I get to see most of the interesting threads, even if they're hardly upvoted.

Today I can't keep up. As the day started I upvoted every joke thread in the 'new' list, but I've long since given up on that. I'm not even able to find every thread in my area of expertise (Breaking of the World|History of Tar Valon); I have to rely on others messaging/mentioning me!